A honing machine is commonly used for finishing a bore in a workpiece. When a workpiece, such as a cylinder, is bored out, the boring tool leaves V-shaped grooves in the surface of the cylinder wall, much like those on a phonograph record. The sharp peaks of these have to be rounded off by finish honing the bore. The typical honing machine uses a set of honing tools spaced around a machine body and fed progressively outwardly into a generally cylindrical internal wall of a workpiece while the machine body is simultaneously rotated within and reciprocated along the workpiece. In this manner, the working face of each honing tool is forced into engagement with the wall under selected honing pressure to abrade and finish the wall.
The specific honing tools usually include a honing element secured in a holder. This honing element is commonly a one-piece element, and in fact is usually referred to as a "honing stone". Examples of such honing elements are described in prior U.S. Pat. Nos. 3,829,299; 2,980,524; 3,352,067; 3,154,893; 3,132,451; 4,528,776; 4,555,875; 3,972,161 and 3,918,218. In the latter two patents, a plurality of cutting filaments are embedded in a matrix, however the resulting honing element is nonetheless a one-piece relatively rigid element.
In the course of honing, it is common for chips or burns to be knocked loose from the cylinder. Because of the solid structure of most honing elements, no clearance is present between the wall and the working face of the honing element. These chips may wedge themselves between the working face of the honing element and the wall. Although a liquid is usually flushed through the bore during honing, such has little effect on the wedged chips. Eventually, either the wall or the honing element must give, resulting in the damage of a honing element or stone and/or the scarring of a bore of what may be an expensive cylinder.
Also many bores such as engine bores have lateral ports. Conventional honing stones or tools cannot radius or finish the edges of such ports. Thus a need remains for an improved honing tool providing improved surface finish.